1. Field of the Invention
This invention relates to a composite material that may be formed into panels having superior ballistic resistant properties and, more particularly, to a resulting composite ballistic material having a very low cost-weight ratio, and a very low cost-strength ratio and without using fiber as the reinforcement.
2. Description of the Related Art
Ballistic resistant articles containing high [tensile] strength fibers that have excellent properties against projectiles are well known. High strength fibers conventionally used include polyolefin fibers, such as extended chain polyethylene fibers; and aramid fibers, such as para- and meta-aramid fibers. For many applications, the fibers may be used in a woven or knitted fabric. For other applications, the fibers may be encapsulated or embedded in a matrix material to form non-woven, rigid or flexible fabrics.
Various ballistic resistant constructions are known that are useful for the formation of hard or soft armor articles such as helmets, structural panels and ballistic resistant vests. For example, U.S. Pat. No. 4,403,012, U.S. Pat. No. 4,457,985, U.S. Pat. No. 4,613,535, U.S. Pat. No. 4,623,574, U.S. Pat. No. 4,650,710, U.S. Pat. No. 4,737,402, U.S. Pat. No. 4,748,064, U.S. Pat. No. 5,552,208, U.S. Pat. No. 5,587,230, U.S. Pat. No. 6,642,159, U.S. Pat. No. 6,841,492, U.S. Pat. No. 6,846,758, and U.S. Pat. No. 7,762,175, all of which are incorporated herein by reference, describe ballistic resistant composites which include high strength fibers made from materials such as extended chain ultra-high molecular weight polyethylene. These composites display varying degrees of resistance to penetration by high speed impact from projectiles such as bullets, shells, shrapnel and the like.
For example, U.S. Pat. Nos. 4,623,574 and 4,748,064 disclose simple composite structures comprising high strength fibers embedded in an elastomeric matrix. U.S. Pat. No. 4,650,710 discloses a flexible article of manufacture comprising a plurality of flexible layers comprised of high strength, extended chain polyolefin (ECP) fibers. The fibers of the network are coated with a low modulus elastomeric material. U.S. Pat. Nos. 5,552,208 and 5,587,230 disclose an article and method for making an article comprising at least one network of high strength fibers and a matrix composition that includes a vinyl ester and diallyl phthalate. U.S. Pat. No. 6,642,159 discloses an im pact resistant rigid composite having a plurality of fibrous layers which comprise a network of filaments disposed in a highly rigid matrix, with elastomeric layers there between. The composite is bonded to a hard plate to increase protection against armor piercing projectiles.
All of these known references involve the use of fibers to build the composites, in the form of a roving, ply, or yarn. However, it has been found that the use of fibers, per se, is not necessary to achieve superior ballistic resistance in a finished product.
Consequently, a need has been felt for providing improved composite material having superior ballistic resistant properties while having no requirement for using fiber as the reinforcement.